Typewriting machine



Aug- 5 1940- w. A. DoBsoN 2.210,570

TYPEWRITING MACHINE Filed May 2, 1938 2 Sheets-Sheet 1 INVENTR WILLIAM A. DUBSON ATTORNEY TYPEWRITING MACHINE Filed May 2, 1938 l 2 Sheets-Sheet 2 INVENTOR WILLIAM A. DUBSON ATTORNEY Patented Aug. 6, 1940 Ulli STAES f PrsN'r risica TYPEVVRITING MACHINE 8 Claims.`

This invention relates to selective line-spacing mechanisms for typewriting machines.

The invention has for its general object the provision of a line-spacing mechanism of simple and rugged construction, assuring dependable service, the mechanism including a line-space-selector device which facilitates the manual setting of the mechanism to effect the desired linespacing.

In its more specific embodiment, the invention provides an improved line-space-selector device including a pawl-throw control arm adapted for fabrication in a single piece and having an overthrow or toggle spring, and deten't means cooperating with the control arm, each capable of manufacture insimple form, presenting a conveniently settable device for controlling the extent of linespace rotation of thetypewriter platen.

In use, the control arm is position-adjustable to either of a plurality of settings, for example, those representing one. two, 4or three line-space selections, the overthrow spring acting on the control arm to yieldably hold same at either side of a medial position, each eccentric position being defined by an abutment or detent which may include anv intermediate recess for yieldably retaining the control arm at the medial position. In each of the mentioned positions, the control arm ,E determines a corresponding action of a ratchet pawl which, upon actuation, moves into engagement with the teeth of a ratchet wheel carried by the platen and causes a rotation thereof to effect the desired line-spacing;

The control arm, by cooperation of the overheld in either eccentric position from which the control arm may be readily moved to another setting by applying manual pressure on a fingerpiece of the arm, sumcient to overcome the power ofthe overthrow spring. Thusgthe operator is relieved from exercising any particular care in setting the mechanism for the desired line-spacing, the control arm and its associated overthrow spring and detent devicecoacting to permit setting the arm to any line-space-dening position by a simple manipulation, and to forcibly hold the arm at the desired setting. l

Other features and advantages will hereinafter appear.

The present invention is in the nature of an improvement `of the line-spacing mechanism shown in my Patent No. 1,908,327, issued May 9, 1933.

In the accompanying drawings: l

Figure 1 is a perspective View of the line-spacing mechanism, certain of the parts being broken away and showing the mechanism set for triple line-spacing.

Figure 2 is a side elevation of the mechanism, viewing same from a point intermediate the William A. Dobson, "Wethersiield, Conn., assign- K;

or toUnderwood Elliott lisher Company, New A l- York, N. Y., a corporaticn of Delaware Application May 2, 1938, Serial No. 205,455

throw spring therewith, is yieldably yet forcibly.

platen ends, the line-spacing.

Figure 3 is a View similar to Figure 2 but showing the mechanism fully actuated.

Figures 4 and 5 are similar to Figure 2, each showing the mechanism in 'initial position and showing respectively the setting of the mechanism for effecting double and single line-spacing, and;

Figure 6 shows the mechanism similar to Figure 2 but with the ratchet detent released.

In 'the drawings, portions of an Underwood typewriter are shown, particularly the related platen carriage thereof, which includes a carriage frame I0 riding on tracks II and an end plate I2 secured to the frame lll, upon which is rotatably mounted a platen I3, the shaft I of which is journaled in the end plate. A ratchet wheel I5 is mountedto rotate with the platen and has the teeth thereof pitched in line-space distances or increments thereof.

The end plate I2 includes a bracket I6 upon which is SWingably mounted, onta stud Il, an arm I8 of a line-space lever I9, the latter having a finger-piece 2i) and being preferably pivotally mounted at 2| on the arm Iii as shown and described in my Patent No. 2,107,370, issued February 8, 1938. It will be seen that the arm I8 and lever IS constitute a bell crank swingable on stud Il in a horizontal plane to actuate aline-space pawl 22 in a manner hereinafter described to rotate the platen I3 a predetermined degree to effect the desired line-spacing ofthe work sheet thereon.

`mechanism being'set for triple The pawl 22 is preferably formed of sheet metal and has a flat body portion on which an ear 25 is bent laterally to carry the stud 24 and provide a broad surface abutting the underside of leverarm I8. At its free end,pawl 22 has a tooth 26 projecting laterally therefrom to overlie the ratchet I 5, normally free of the teeth thereof. A pawl-restoring spring 2l engages the pawl ata lug 28 thereof and is anchored to the end-plate I2 as by'a post 29, the spring being arranged to pull the pawl forwardly in restoring same to normal quiescent position, as shown in Figures 2, 4 and 5, and with it the associated line-space lever I9 after manual actuation of same. The arrangement of spring 21 is such that same also tends The free end of arm III has a cylindrical aperl to swing the pawl downwardly to urge pawl tooth 26 toward the ratchet wheel I5.

During actuation, in effecting the desired linespacing rotation of the platen selectively to a single, double or triple line-space, the pawl moves a uniform distance for any selected line-space. The forward or quiescent position of the pawl 22 may be determined by the arm I8 of lever I6 abutting a shoulder 36 ofthe end-plate I2, see Figures l and 2. In the full actuated position of pawl 22, the pawl tooth 26, after engaging a ratchet tooth. comes against a stop 3| on enol-l plate I2, the stop face 32 of which is inclined in relation to the direction of approach of pawl tooth 26 so as to cam or wedge same downwardly against the engaged tooth of the ratchet wheel I in such manner as to prevent any overthrow of the ratchet wheel as may result from momentum of the platen as sarneis brought to rest.

The amount of line-spacing is selective, and is controllable by a line-space selector device 35 cooperating with the pawl 22, the selector device including a plate-like arm 36 having a slot 31 preferably open and engaging the platen shaft .i4 to provide a swingable and endwise movable mounting for the arm 36, a side of which may lie against the inner face of end-plate I2. Arm 36 is flanged at 38, the flange being stepped to form a shoulder at 39 disposed to engage the bottom edge of the pawl 22. It will be observed in Figure 1, that the flat body portion of the pawl 22 is disposed between and in contact with both the end of a collar 34 adjacent the ratchet wheel l5, and the contiguous portion of the flange 38, the collar 34 and flange 3B jointly forming a guide groove, retaining the forward portion of pawl 22 against excessive lateral displacement although affording ample clearance for same to accommodate the slight lateral oscillation of pawl 22 as required by the arcuate path of stud 24.

By disposing the arm 36 in one of a plurality, preferably three selective positions, the position of arm shoulder 33 so varies the operation of the pawl 22 as to cause same to rotate the platen one, two or three line-spaces, that is by rotating the ratchet wheel I5 a corresponding number of tooth pitches. By setting arm 36 as shown in Figure 5, for single line-spacing, actuation of the pawl 22 will bring pawl tooth 26 into engagement only with ratchet tooth I 5', tooth 26 being caused to pass over the preceding teeth by the actionof shoulder 36 with the bottom edge of pawl 22, which edge is formed as a cam to guide tooth 26 in a prescribed path above the ratchet wheel until in position to engage toothA I5.

' In the setting of arm 36 as shown in Figure 4, that is, for double line-spacing, the pawl tooth 26 will be caused to .engage ratchet tooth I52 and thus the platen will be rotated two linespaces. Setting of arm 36 in position shown in Figure 2 will cause pawl tooth 26 to engage the ratchet tooth I53 and thus rotate the platen a distance of three line-spaces.

In each setting of arm 36, the coaction of' pawl 22 with shoulder 39 is `substantially similar, the pawl, pressed toward the shoulder by spring 21, sliding over the shoulder as the pawl is actuated rearwardly, the pawl tooth 26 being allowed to lower into the appropriate ratchet tooth for rotating the platen the .desired line-space degree in accordance with the setting of the line-space selector arm 36.

Arm36 is extended to provide a finger-piece 46, the arm being offset at 4I to form a shoulder disposed within a slot 42 in the end plate I2, the

finger-piece 46 being thereby disposed at the outside of plate I2 for convenient access by the opv erator. Slot 42 is arcuately formed substantially abutment of arm portion 4I with the respective ends of the slot, the slot extending either side of a medial position of the arm as shown in Figure 4.

The yieldable retention of arm 36 in position at either extreme of the arc as defined by the limits of slot 42, is effected by a suitable spring, preferably a compression spring or resilient loop 43 having its respective ends articulated to the arm 36 by stud 44, and to a stationary member such as the plate I2 by stud 45. As shown more clearly in Figure 4, the studs 44, 45 are in a line radiating from the axis I4, with the arm 36 in its medial position. It will be seen, therefore, that spring 43, together with a portion of arm 36, constitutes a toggle of which one link, the spring 43, is resilient. The toggle action effected by the resilience of spring 43, urges arm 36 to swing eccentrically of its medial position, that is, toward either extreme of its limited arc, or against either end of the slot 42, as shown respectively in Figures 2 and 5.

The depth of arm slot 31 is such that spring 43 presses arm shoulder 4I against the contiguous edge of slot 42 with the arm in either extreme position, the friction of shoulder 4I on the slot-edge, assisting the spring in resisting movement of the arm 35. 4At medial position, the slot 42 has a recess or notch 46 into which the rounded shoulder 4I seats, being pressed therein by the action of spring 43 to yieldably retain the arm 36 intermediate the ends of slot 42, see Figure 4.

Accurate detenting of the platen at each typing line is effected by a detent roller 41 cooperating with the teeth of ratchet wheel I5, the roller being carried on an arm 46 pivoted on a stud 49 secured to the plate I2, the mounting of arm 48 to the stud being readily removable by providing a yoke 56 having a U-shaped slot straddling the stud 49. Arm 48 extends laterally at 52, the extending portion being bent around to provide an outer bearing for the roller 41. A spring 53 is seated in a recess in the carriage frame I6 and engages the arm portion 52 to press detent roller 41 into the teeth of ratchet wheel I5, the spring serving also to press arm 48 so as to maintain the yoke 56 in association with stud 49.

For fractional line-spacing, a detent release lever 54-is provided, the same being pivoted on the plate I2 by a stud 55 and having a restoring spring 56 tending to hold lever 54 in ineffective position against a stop 51, as shown in Figure 2, the respective ends of the spring engaging the lever and a fixed member of the platen carriage. The release lever 54 carries a friction shoe 58 swingable into engagement with the free end of a finger 53 of the detent roller arm 48 to wedge the arm by a toggle action so as to retract the roller 41 from the ratchet wheel I5. The friction of the shoe 53 against the end of finger 53, augmented by the pressure of spring 53, latches the parts as shown in Figure 6, against the power of spring 56 until manual actuation of the lever 54 towards stop 51 overcomes the friction to release detent roller arm to normal eifective position. Only a slight touch of lever 54, suicient to overcome the friction, is ample to permit spring 56 to swing lever 54 to ineffective position, in which position shoe 58 is entirely free of finger 58 and the latter may therefore move unencumbered during the normal detenting action of arm 48.

The invention is not confined to the exact embodiment shown in the drawings nor to the precise details of construction illustrated therein, but certain modifications and changes may be made within the spirit or scope of the invention as expressed in the appended claims.

I claim:

i. In a variable line-spacing mechanism for typewriting machines, having a pawl and ratchet device and actuating means therefor, in combination, a line-space selector element adapted to control the extent of throw of the pawl, and swingable in a limited are to either of two pawlthrow determining positions, and a toggle device including a resilient link operatively associated with said element to yieldably hold said element in either position.

2. In a variable line-spacing mechanism for typewriting machines, having a pawl and ratchet device and actuating means therefor, in combination, a line-space selector element adapted to control the extent of throw of the pawl and swingable to either of two pawl-throw determining positions, an overthrow spring cooperating with said element to yieldably hold said element in either position, and a fixed member presenting an arcuate edge substantially .concentric with the axis of said selector element, said element including a part pressed by said spring into frictional contact with said edge to assist said overthrow spring in holding said element in either position.

3. In a variable line-spacing mechanism for typewriting machines, having a rotatable platen, a shaft carrying the platen, a carriage member supporting the platen shaft, a pawl and ratchet device for line-space rotation of said platen and actuating means therefonin combination, an arm adapted to control the extent of throw of the pawl and swingable to either of two pawl-throw determining positions, said carriage member presenting an arcuate edge with abutments at the ends thereof, said arm including an offset shoulder engaging the arcuate edge of said carrying member and limiting the swing of said arm by engaging said abutments,and an overthrow spring cooperating with said arm to yieldably hold the arm shoulder in either abutment engaging position.

Il. In a variable line-spacing mechanism for typewriting machines, having a pawl and ratchet device and actuating means therefor, in combination, a line-space selector element adapted to control the extent of throw of the pawl and swingable in a limited arc to either of two pawlthrow determining positions, an overthrow spring cooperating with said element to yieldably hold said element in either position, and means enabling said spring to yieldably retain said element in a third pawl-throw determining position intermediate the two said positions.

5. In a variable line-spacing mechanism for typewriting machines having a rotatable platen, a shaft carrying the platen, a platen-carriage member supporting the shaft, a pawl and ratchet device for line-space rotation of the platen and actuating means therefor, in combination, an

arm adapted to control the extent of throw of the pawl and swingable to a plurality of pawlthrow determining positions, said carriage member having an opening presenting an arcuate edge tereminating in abutments at the ends thereof and a notch intermediate the ends, said arm inciuding an offset member engaging the arcuate edge of said carriage member, and an overthrow spring cooperating with said arm to yieldably hold the odset member against either abutment or in the notch, whereby to detent said arm in any selected position.

6. In a variable line-spacing mechanism for typewriting machines having a rotatable platen, a shaft carrying the platen, a ratchet wheel on the platen and a carriage end-member supporting the platen shaft, in combination, a reciprocatory pawl cooperative with the ratchet wheel to `rotate the platen in line-spacing, means operative at one end ofsaid pawl for actuating said pawl in uniform extents of stroke, a line-spacing selector arm mounted for swingable and endwise movement on the platen shaft, including an offset shoulder, said pawl having a cam-shaped edge'engaging said arm shoulder and cooperating 'therewith to denne different paths for said pawl in accordance with the setting of said arm-shoulder, and means for yieldably holding said arm in one of a plurality of line-space defining positions, said arm being disposed adjacent the ratchet wheel and forming a groove therewith for guiding the free end'of said pawl.

'7. In a variable line-spacing mechanism for typewriting machines having a rotatable platen,

shaft carrying the platen, a ratchet wheel on i the platen and a carriage end-member supporting the shaft, in combination, a reciprocatory pawl cooperative with the ratchet wheel to rotate the platen in line-spacing, means operative at one end of said pawl for actuatingv said pawl in uniform vextents of stroke, a line-spacing selector arm mounted for swingable and endwise movement on the platen shaft, including a shoulder, said pawl having a cam-shaped portion engaging said arm shoulder and cooperating therewith to denne different paths for said pawl in accordance with the setting of said arm shoulder, an oifset member on saidarm, said carriage end-member presenting an arcuate edge engageable by said offset arm-member and having end abutments and an intermediate notch to detent said arm at selective positions, and an overthrow spring pressing said arm toward the arcuate edge and adapted to yieldably hold said arm-member against either abutment or in the notch.

8. In a variable line-spacing mechanism for typewriting machines having a platen carriage, a platen shaft on the carriage and a pawl-andratchet device for line-space rotation of the platen, in combination, a control member adapted to regulate the extent of throw of the pawl and pivoted on the platen shaft to swing in a limited arc to a plurality of pawl-throw-determining positions, said control member presenting an operating arm having a finger-piece at its free end, and a compression spring articulated to the carriage at a point farthest remote from the arm` pivot and to said arm intermediate the said point and the arm pivot, the points of articulation being on a common line with the arm pivot with said arm in a medial position.

WILLIAM A. DOBSON. 

